8. Eligibility for gamma-knife radiosurgery: The decision to treat with gamma-knife radiosurgery will be made by a consensus of the radiation oncology, neurosurgery and neuro-oncology co-chairs or their alternates at the weekly Brain Tumor or Gamma-Knife Tumor Conferences. The MRS defined target volume must be ≤ 15 cc. and not involving eloquent brain (speech/language cortex, motor/sensory cortex, basal ganglia, brainstem, or corpus callosum 2) on an MRI done within 14 days of the planned GKS procedure.